See here:
The Clinton Doctrine was “more expansive than Bush’s NSS”, but it was “barely even reported”, since it was “presented with the right style” and “implemented less brazenly”.
Regarding the two instance of "it" that come after I introduce a second doctrine (the one from W. Bush), I have to worry that it might be possible to link them back to the second doctrine instead of to the first one. But the second doctrine is mentioned in a "than" construction, so maybe there's a hard-and-fast rule that the two instances cannot link to something inside the "than" construction; I hope so.
One extra question too, if that's OK. I write "but it was" and "since it was" in order to be symmetrical or parallel or whatever. But I could write "but was" (and drop the "it" there); would it be advisable to drop that instance of "it" even if doing so would make it asymmetrical or non-parallel or whatever because I can't also say "since was"?